I was never able to get uVNC to do MS Logon authentication without writing a bat file to configure the client. The only way I found to get NT authentication to work was to use the New MS Logon and to use the mslogonacl.exe to add the users after creating the registry key to put them in. It took some digging in the forums to find this information and after testing and playing with things for several months, things are working reliably.